Ionizable effects

Cone-voltage fragmentation Fragmentation of ions, commonly produced by APCl or electrospray ionization, effected by the application of a voltage within the source of the mass spectrometer. 

The formal potentials ( ° ) of the three kinds of SODs were found to be dependent on solution pH as displayed in Fig. 6.6. As shown, the formal potential of bovine erythrocyte Cu, Zn-SOD decreases linearly with increasing solution pH with a slope of ca. -60mV/pH from pH 5.8 to pH 9.5 (curve b), indicating one proton and one electron are included in the electrode reaction of Cu, Zn-SOD, which is similar to previously proposed enzymatic catalytic mechanistic scheme of the Cu, Zn-SOD [139— 144], In contrast, the pH dependency of Fe-SOD from E. coli was complicated (curve a) the formal potential changes linearly with solution pH in a range from pH 5.8 to 8.5 with a slope of ca. -60mV/pH, and becomes pH-independent at above pH > 8.5. Previous studies have observed that the Fe (III) form of the protein ionizes with an apparent pKa of 9.0 0.3 and such ionization effect has been interpreted in terms of hydrolysis of a bound water molecule with p/<"a of ca. 8.5 [145], The C -pII profile of... 

When spread from dilute hexane solution, acid-dependent enantiomeric discrimination was observed in the 11/A compression isotherms of the monolayer at 25°C (Fig. 12). It is interesting to note that at higher subphase acidities, both racemic and enantiomeric film systems become more highly expanded, and the surface pressures where enantiomeric discrimination commences occur at high (85-90 A2/molecule) average molecular areas. This may be taken as direct evidence of headgroup ionization effects. The surface... 

Pure mobile phases with organic precipitants produced the largest ionization effects (Table 1.16). 

Variation of Ionization Effects of Acetonitrile in 50 50 Methanol/Water (2 1)... 

Plasma Type Ionization Effect (%) Duration of Ionization Effect (min)... 

Ionization Effects of Various Protein Precipitant and Mobile Phase Combinations on Human Plasma... 

What is one of the disadvantages of APCI How does this disadvantage manifest itself (only a limited variety of reagent ions can be produced from common HPLC eluents many of those eluents produce reagent ions that are relatively weak gas-phase acids, which limits the range of compounds that can be ionized effectively). 

Radiations, Ionizing, Effects on Some Fibrous Proteins Vol. Page... 

Atomic absorption spectroscopy is highly specific and there are very few cases of interference due to the similar emission lines from different elements. General interference effects, such as anionic and matrix effects, are very similar to those described under flame emission photometry and generally result in reduced absorbance values being recorded. Similarly, the use of high temperature flames may result in reduced absorbance values due to ionization effects. However, ionization of a test element can often be minimized by incorporating an excess of an ionizable metal, e.g. potassium or caesium, in both the standards and samples. This will suppress the ionization of the test element and in effect increase the number of test atoms in the flame. 

Alpha particles are relatively large particles and are emitted with a limited number of energy levels. They carry a double positive charge and as a result attract electrons from the atoms of the material through which they pass, causing ionization effects. They have an extremely short range, even in air, and as a result present very little hazard as an external source of radiation but their effects within living cells or tissues can be serious. 

Some substances, known as fluors or scintillants, respond to the ionizing effects of alpha and beta particles by emitting flashes of light (or scintillations). While they do not respond directly to gamma rays, they do respond to the secondary ionization effects that gamma rays produce and, as a result, provide a valuable detection system for all emissions. 

The unification and direction which the P concept gave to metabolic studies led to its rapid and enthusiastic adoption by the new generation of biochemists starting work after the end of World War II. Kalckar suggested the contribution resonance stabilization might make to the distinction between the two classes of phosphate compounds. T.L. Hill and Morales (1951) identified ionization effects and electrostatic repulsion as further possible contributants to the net differences in free energy between products and reactants. 

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